EARTH
This sequence of images taken by the Hubble Space Telescope shows that the North Star, Polaris, is a triple star system. New research also confirms the main North Star is a Cepheid variable. IMAGE/NASA, ESA, N. Evans (Harvard-Smithsonian CfA), and H. Bond (STScI)
The North Star, the Pole Star, the Guiding Star, Polaris: Its many names reflect the many centuries humans have gazed northward to it for guidance. Because Earth’s North Pole is aligned with Polaris’ position in the sky, the star appears motionless, providing a steadfast beacon for early sailors and adventurers alike. But the star itself is far from motionless. In fact, Polaris is a specific type of star known as a Cepheid variable, which pulsates, varying in size and luminosity over a period of days and, according to recent observations, also ejects large amounts of mass into space. Now, combining 170 years worth of observational data on Polaris’ pulsation rates with state-of-the-art stellar evolution models, a team of scientists suggests that Polaris is losing mass at a significant rate. But this does not mean Polaris will vanish from the night sky anytime soon.
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